Activities

1. At first, just a single charge is present, and there is also a small positive test charge that you can drag around the screen to sample the electric field and the electric potential at any one point. The charged object can also be dragged around the screen. Note that you can change the charge on the charged particle by using the "Charge on particle 1" slider. If you reduce the charge on the charged particle by a factor of 2, what happens to the electric potential everywhere? If you increase the distance between the charged particle and the test charge by a factor of 2, what happens to the electric potential at the location of the test charge? If you flip the sign on the charge of the charged particle, while keeping the magnitude of the charge the same, what happens to the electric potential everywhere?
2. Now, explore what happens when there is a second charged particle present, by moving the "Number of charges" slider to 2. Choose a particular sign, magnitude, and position for charge 1, and a particular sign, magnitude, and position for charge 2, and then position the test charge somewhere. Note that you can turn off the first charge by setting its charge to zero, and you can turn off the second charge either by setting its charge to zero, or by re-setting the "Number of charges" to zero. Record the electric potential at the position of the test charge from charge 1 only, from charge 2 only, and then when both charge 1 and charge 2 are turned on. Describe how the net potential, when both charges are on, is obtained from the individual potentials. Compare this method of finding the net electric potential with the method for finding net electric field.